Rotary drilling method



March 13, 1956 D. D. SHIELDS ROTARY DRILLING METHOD Filed Aug. 21, 1953 i ATTEST INVENTOR.

DARVIN D. SHIELDS.

"Maw

ATTORNEY Statcs Patent v 2,738,163 ,ROZ ARYIDRIL ING METHOD Duvin 'D. "Shields, Dallas, Tex, assignor to The Atlantic Refiningtflompany, Philadelphia, fPa., a corporation of Pennsylvania final sa i n A gus 21, 1 eri l e-3 .7560

s Claims. crass-1,8

, This .insent nn pertain t an mprovem in t drilling of boreholes, such as .oil wells or seismic shot heleahy the rotary dr li m th d ndp r i ular to an improvement in such method wherein ,gas, such .as an. t'aen h t ensas, t i p d a th ai leu atin flu d for coolin the rill it an tor e ins Batente Ma r1i-1-956 t ease of e alte io i e treme y mi im tes- It .is van object of' this invention to provide limmo ed niethafl o i l ng a a th s mulatin fluid, which method does not require the use .of water e n)"v othe l qu d dur n an pa t o h dril ng ar n tion.

t is a th the o ject of this i v h ut p es de an in pre edme hot of sh ll g th ou st cky mations, such as damp clay formations, which are stnuck by the dr l b t du in drilli by t a y dri g method in lh e .sa iis used a the circulating fl i aute tt nss Although ve her a may justi y t e e 2 f ah q as, n tead 91 a l id, a a dr lin nun, the use thereof has been most prevalent in areas where water is scarce or unavailable sothat it must be hauled in .m th well site pver' great distances, and in those areas impossible or impractical.

A thou d i lin us n as h circulating ui has prayed to be substantially ,as satisfactory,-nnder mo st cond tions, as wh n q i s a h i u in tl uid,y.considerable diflicultfy has been experienced in drillins hrenahe tai type o rm o s c as d p clay, whic onta en u h s u e s h tha t i ,terial cuttherefrom by the drill bit is sticky andtends .to ffonn into relatively large masses and adhere to the drill bit. It has heentound that dry ;f0rmafi0ns .oficr no problem because the chips or cuttings thereitom be- $98.16 entra ne in the circul i ga st eam and are d to the suface therehyL 0n the other "hand, forns which ,contain water in substantial quantities 0 problem because the excess of water causes talent-hem h r at-i n to as um the t rm 9 a Mahmu w eh c e ek n up y t e ,ilowing stream and carried to the suface the form of droplets. V

Prior to this invention, it was the practice, when using gas asthe circulating fluid for a drilling well, to main- .a supply of water or other liquid attire well site, and when st ck ,f i i n eh as e mpr ns damp clay was struck, to flow into the gas supply line for circulation through the well, an amount of liquid liu sufiicient quantity to form the material cut from the formation into a thin mud capable of being borne to the surface by the circulating gas.

While thismethod of drilling through formations comprising sticky materials has proved generally satisfactory it still has the disadvantage of requiring the presenc l i Wa ha th t h ehnle, i h m y be extremely expensive or impractical, as in the case where wat r is lo ated only a a ons e bl di t ne the site, or nevbe s bstant a ly mpossib e, ssin re extreme cold makes the use of liquid drillii g fluids pressor 13.

Another object is to provide an improved method of d ill n thren h tic y fo mat on nciden 0' th l n of lh r l e by th nota y m thod us n gas as the s re tins pfiu d. y injectin a quant y as a finely d ded .sQ id substance, s ch as a y ha t p tiei es nt th s mu tin a st e du in the. t m wh n t d il bit Iis pa in h oug s ch orm t on O he o je ts and advan a e ef the inve tion willhecome .apparent from the following description taken-in a n e e w t the appe d dr w ng.

T e dra n i a sch mati .rep ese ta a p t ly i s ss o o equipm n whic may b inp ley int dr l n of a o e o ac an e w t t e me!:h d

f thi in nt on B i fly h s n en ion i e nei net i h an inn-nov ment in 'the method of drilling boreholes in the earth by the rotary drilling -method wherein a gas, rather than a fliguid, is employed as the circulating medium for carryingto the suiace' particles of material dislodged by the d il u in dri l n -i fB emafly, th n ent en. ha

.to do' with facilitating drilling through sticky jforma tons, such as danrpclay formations, the cuttings of pwhich tend to tormfinto large sticky masses and to ad-, here to the drill hit and to the walls of the borehole.

According to this method, when formations of this type are struck by the drill bit, :a quantity'of a finely divided solid dry substance is introduced into the gas stream, whereby 'to. be carried to the sticky formation. It has been found that such particles carried by the circulating gas substantially-prevent the material cut'from sticky formations from forming into large masses, and instead cause them to term into pellets coatcd by the particles, and which have substantially no tendencyto stick to each other or to the well bore'or drill-bit, and whic'hare capable of being carried to the surface by the circulating gas stream.

In the d'rIaWin-g'there is shown one embodiment of an apparatus which may be employed in carrying out the method of this invention. The numeral 1 designates a kelly to which is attached a drill string 2 and drill "bit ,3 and which'is adapted to be rotated by a rotary table,

not shown, mounted in platform 4. The kelly 1 is connected by a suitable coupling 5 to a swivel 6 supported by a bail -7 from the hook 8 of a traveling block 9. The gooseneck lo of swivel 6 has secured thereto one end of a flexible hose 11, the other end of which is connected with a conduit 12 which is adapted to be supplied with air or other gas under pressure from com- Preferably, a gauge '14 is connected into conduit 1-2 for indicating the pressure existing therein.

'So far as the purpose of this invention is concerned, it is immaterial whether compressor 13 is adapted to supply air, or some other gas to conduit 12, and also the pressure and volume of gas which is adapted to be supplied by compressor 13 and circulated through the system is immaterial so long as such pressure and volume'iare withirinhefiange normally employed in drilling operations of this type. In a typical instance, it has-been --,fonnd satisfacto y to ei i ley a eatnpse se e ra e of del ring euhi lt e o ass pe m nute at pre 3 sure of 25 p. s. i., gage, in drilling a hole of 4% inches diameter using a 2% inch, 0. D. drill stem.

Conduit 12 is preferably provided with a lateral nipple 15 to which is secured, as by flanged connection 16, a metering dispenser 17 having a flanged connection 18 with a bin 19, which is adapted to contain a quantity of dust or similar finely divided solid dry particles 20 for introduction into conduit 12, as will be explained in more detail hereinafter. Bin 19 is provided with opening 21 at its upper end to facilitate reloading of the bin as well as to maintain the interior of the bin at atmospheric pressure so that there will be no tendency to create a vacuum as the dust or other particles are dispensed therefrom by dispenser 17.

Although the dispenser per se forms no part of the present invention, and while numerous other types of dis pensers might be suitable for use, one such as dispenser 17 shown in the drawing is thought to be most satisfactory for use in connection with carrying out the method of the invention. It will be obvious that rotation of compartmented rotor 22, by any suitable manual or automatic means, not shown, will result in dispensing into conduit 12 the contents of the several compartments 23 of the rotor which are in turn refilled by gravity flow from the bin 19 upon continued rotation of the rotor. The ends and the radially outer edges of the compartment walls 24 of rotor 22 are preferably provided with a lining of a suitable resilient packing material, not shown, having a tight fit with the interior wall of the dispenser body whereby to form a seal therewith in order to isolate the interior of bin 19 from the pressure existing in conduit 12.

In describing the method of the present invention in connection with the apparatus shown in the drawing, it will be assumed that drilling is progressing normally through formations other than one comprising moist clay or similar sticky material. Under such conditions air or gas would be flowing from compressor 13 through conduit 12, hose 11, swivel 6, the bore of kelly 1 and-drill pipe 2, thence into the borehole 25 through ports 26 in the drill bit 3 whence it will flow upwardly through the borehole and outwardly through nipple 27 secured in the wall of surface casing 28, and hose 29 to waste pile 30, carrying with it cuttings dislodged by the rotation of drill bit 3. During this time the rotor 22 of dispenser 17 is maintained stationary thus retaining the particles20 within bin 19 and preventing their entry into conduit 12.

Assuming that the drill bit 3 now strikes a formation comprising moist clay or a similar material which does not break up into small chips capable of being carried out of the borehole by the gas stream emerging through ports 26, that fact will be indicated by an increase in pressure in conduit 12 as shown by pressure gauge 14. This increase in pressure is brought about by the fact that sticky materials of the nature of moist clay seem to form into large masses which adhere either to the drill stem and to the wall of the borehole, thus obstructing the escape of the gas upwardly, or else adhere to the drill bit clogging the ports and thus preventing the escape of the circulating gas therethrough. Substantially immediately upon noting a sustained rise in pressure in conduit 12 as indicated by pressure gauge 14, the drill bit is lifted sufficiently to raise it clear of the troublesome formation in order to permit re-establishment of normal circulation of the gas, and thereafter rotation of rotor 22 of dispenser 17 is commenced whereby to dispense into the gas flowing through conduit 12 a quantity of the particles 20 contained in bin 19. After waiting a sufficient time, depending upon the rate of flow of the circulating gas and the depth of the troublesome formation, for the solid particles dispensed from bin 19 to reach the drill bit and be gin being exhausted therefrom, drilling is recommenced, with the drill bit being advanced through the sticky formation.

It has been found that finely divided solid dry particles thus discharged through the ports of the drill bit into contact with formations comprising sticky material become intermixed with the material and form a coating thereon which prevents it from sticking either to itself to form large masses, or to the drill bit or walls of the borehole. The combination of the action of the drill bit, the agitation caused by the flowing gas, and the presence of the finely divided solid particles results in the material cut from sticky formations being formed into relatively small substantially dry pellets having a coating of the finely divided particles, which pellets are capable of being lifted to the surface'and discharged to the waste pile by action or" the gas rising through the well bore.

Since the nature of the troublesome sticky formations which may be encountered, but which may be drilled through in accordance with the method of this invention may vary widely as to moisture content, adhesive and cohesive tendenices, and other characteristics, and since the nature of the finely divided solid particles which may be available for use may vary considerably, no definite limitations which would be valid for all cases can be placed upon the amount of the finely divided material which must be dispensed into the flowing gas stream. In general, the rate of dispensing the finely divided particles into the gas stream should be high enough to prevent any substantial increase in the back pressure on conduit 12 over that existing when drilling is in progress through normal dry formations. This will indicate that the material is being disintegrated into small enough non-sticky pellets to facilitate removal to the surface by the circulating gas, since otherwise material accumulating in the bottom of the borehole in a large mass would obstruct the flow of gas, causing the pressure in conduit 12 to rise. The dispensing of the particles into the gas stream should be continued until the drill bit has completely penetrated the troublesome formation, as will be indicated by the nature of the cuttings exhausted from exhaust hose 29.

Although the substance comprising the finely divided solid particles 20 should preferably be one which is highly moisture adsorbent, such as fullers earth or activated bauxite, substantially any finely divided solid substance may be used for this purpose provided only that it is of such a nature as to adhere to and form a coating on, sticky earth materials, such as moist clay. Other materials suggested for use, although the list is not intended in any manner to be exhaustive, are finely divided particles of substances such as limestone, sandstone, talc, chalk, gypsum, dry clay, and sand. Preferably the material should be in the form of a fine dry dust with particle sizes on the order of mesh, although satisfactory results may be obtained with particles ranging to the size of coarse sand.

From the foregoing it will be seen that this invention provides a method for drilling through sticky formations, such as moist clay, while using gas as the circulating fluid, by introducing into the fluid dry solid particles in sufficient quantity to render the sticky material substantially non-sticky and to cause it to form into pellets of relatively small size which can be borne to the surface in substantially the same manner as cuttings dislodged from other types of formations.

It will be obvious to those skilled in the art that variations in the disclosed apparatus and method may be made without departing from the spirit and scope of the invention. Therefore, the invention is not to be considered as limited in accordance with the foregoing description but only in accordance with the appended claims.

I claim:

1. In the rotary drilling of boreholes wherein gas is used as the circulating fluid for carrying drilled material from the borehole, the method of drilling through a formation comprising moist clay or similar cohesive and adhesive material which tends to form into large masses and to stick to the drill bit and drill stem and thus resist removal to the surface by said circulating fluid, which method includes the step or introducing into said fluid during the time when the drill bit is passing through said formation an amount of finely divided solid dry particles of a substance capable of adhering to said material in sufficient quantity to cause said material to form into relatively small non-sticky masses having a coating of said particles and capable of being borne upwardly out of said borehole by said circulating fluid. V

2. In the rotary drilling of boreholes wherein gas is used as the circulating fluid for carrying drilled material from the borehole, the method of drilling through a formation comprising moist clay or similar cohesive and adhesive material which tends to form into large masses and to stick to the drill bit and drill stem and thus resist removal to the surface by said circulating fluid, which method includes the step of introducing into said fluid during the time when the drill bit is passing through said formation an amount of a finely divided dust of a substance capable of adhering to said material in sufficient quantity to cause said material to form into relatively small dustout of said borehole by said circulating fluid.

3. In the rotary drilling of boreholes wherein gas is used as the circulating fluid for carrying drilled material from the borehole, the method of drilling through a formation comprising moist clay or similar cohesive and adhesive material which tends to form into large masses and to stick to the drill bit and drill stem and thus resist removal to the surface by said circulating fluid, which method includes the step of introducing into said fluid during the time when the drill bit is passing through said formation an amount of a finely divided dust of a moisture adsorbent substance capable of adhering to said material in sufficient quantity to cause said material to form into relatively small dust-coated non-sticky masses capable of being borne upwardly out of said borehole by said circulating fluid.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN THE ROTARY DRILLING OF BOREHOLES WHEREIN GAS IS USED AS THE CIRCULATING FLUID FOR CARRYING DRILLED MATERIAL FROM THE BOREHOLE, THE METHOD OF DRILLING THROUGH A FORMATION COMPRISING MOIST CLAY OR SIMILAR COHESIVE AND ADHESIVE MATERIAL WHICH TENDS TO FORM INTO LARGE MASSES AND TO STICK TO THE DRILL BIT AND DRILL STEM AND THUS RESIST REMOVAL TO THE SURFACE BY SAID CIRCULATING FLUID, WHICH METHOD INCLUDES THE STEP OR INTRODUCING INTO SAID FLUID DUR- 